As the governor looks to his own reelection in November, the choice he makes to fill Lautenberg’s seat will send a national message, writes John Avlon.

New Jersey Sen. Frank Lautenberg, who had been the last surviving World War II veteran in the U.S. Senate, is dead. And that means Gov. Chris Christie will need to appoint a successor until a special election, likely to be held this November.

Sen. Frank Lautenberg (D-NJ) listens to a question in May 2009 in Trenton. Lautenberg died Monday at age 89. (Mel Evans/AP, Mel Evans)

For Christie, it’s a decision piled high with political risks: he’s running for reelection this fall and eyeing a run for president in 2016. Whom he picks will send a message not just to New Jersey, but to the nation. Here is NewsBeast’s list of five contenders who are just a stroke of a pen away from joining the world’s most exclusive club.

Tom Kean in March 2011. (J. Scott Applewhite/AP)

Tom Kean: The perfect caretaker candidate, Kean is a broadly respected icon in New Jersey politics and a Christie mentor. Best known nationally for serving as co-chairman of the 9/11 Commission, he embodies the endangered species that is the Northeast Republican—of which Christie is the most vibrant current specimen. He is responsibility personified.

Tom Kean Jr. in January 2012. (Mel Evans/AP)

Tom Kean Jr.: No, this is not a typo. The son of the former governor and current state senator ran for U.S. Senate in 2006. Considered a rising statewide Republican star and Christie ally, this pick would set up a fight for the Senate seat in the fall against Newark Mayor Cory Booker, who would be regarded as the odds-on favorite. And a strong Booker showing at the ballot box this fall could eat into Christie’s huge lead in his own race.

Lieutenant Gov. Kim Guadagno: If the aim of the Senate appointment is to do no harm, moving New Jersey’s lieutenant governor up to the U.S. Senate for a time could be a good move. A former federal prosecutor and sheriff, she has legal and law-enforcement credentials and knows the Christie-administration agenda cold. And it doesn’t hurt to appoint a woman to the office when you’re aiming to close the gender gap in a reelection to make a national point.

Christine Todd Whitman in September 2008. (Susan Walsh/AP)

Christine Todd Whitman: Two decades ago, then-governor Whitman was considered—along with Massachusetts Gov. Bill Weld and New York City Mayor Rudy Giuliani—the standard-bearer for Northeast Republicanism. Like Kean, Whitman, who served as George W. Bush’s EPA administrator after leaving the governorship, would be an unobjectionable caretaker for the position and offer some national resonance. Unlike the Keans, though, she is not a particularly close Christie ally.

Newark Mayor Cory Booker in May 2013. (Jessica Hill/AP)

Cory Booker: Bear with me. Booker and Christie have formed a constructive and cordial working relationship, especially on issues like education reform, where Booker has taken on the teachers unions and backed school choice. This pick would forestall a big fight in the fall and instantly embody Christie’s national promise as a leader beyond party. But of course it would increase conservative attacks on Christie as a traitor to the cause. It might help add to his margin in his New Jersey reelection—remember that Republicans run a distant third in party registration to independents and Democrats—but it could be credibly described as suicidal in an Iowa caucus or a 2016 GOP primary. So consider this a side shot: unlikely but inspired.

There’s always the chance of an inside Jersey power play, an old friend or a judge. There will also be calls to appoint a member of the Republican congressional delegation like Chris Smith (whose social conservatism, especially on abortion, could hurt Christie’s short-term concerns) or Rodney Frelinghuysen—both of whom could lead to a Democratic pickup of their congressional seat, providing Christie with a perfectly good excuse to go elsewhere.

Any list is premature, and only Christie knows for sure—he has all the power here, and aspirants must appeal to a constituency of one. But the pick will help define Christie’s national profile and shape the dynamics surrounding what looks like a landslide reelection this fall.